1. Field of the Invention
The present invention relates to a method and composition for creating a smooth, hard surface finish on building structures, particularly upon structures formed of concrete.
2. Description of the Prior Art
At present many building structures are constructed with large areas of upright and overhead concrete supports. Concrete has been used in the construction of building walls, ceilings and floors for centuries. The use of concrete for large, expansive surface areas of building walls, ceilings and floors is advantageous, since concrete can be internally reinforced with iron or steel, and since concrete, once cured, is impervious to moisture, does not rot, and is not affected by fire, insects or flooding. Concrete is exceptionally durable and is currently widely used in the construction of large public buildings, such as parking garages, office buildings, sports stadiums, convention centers and in other buildings utilized for many different purposes
Although concrete has the desirable properties of a construction building material hereinbefore described, it does have a surface finish, which if untreated, is undesirable. The surface finish of unfinished concrete is rough and abrasive. Persons coming into contact with it are subjected to a high risk of receiving cuts, scrapes and skin abrasions. Furthermore, the surface of unfinished concrete is not aesthetically appealing. Also, unfinished concrete is extremely difficult and expensive to paint. The roughness of the surface greatly increases the labor expense involved in painting, due to the extensive time required to paint a given surface area. Moreover, a very large quantity of paint is required to cover a relatively small surface area of concrete.
To alleviate the problems presented by concrete surfaces, at least the interior concrete surfaces of building structures are currently finished with a conventional concrete finishing compound in order to retain the structural benefits of concrete, while masking the surface appearance of concrete within the structures. At present a patching cement mixture is normally utilize in order to fill in holes in concrete surfaces and to improve the surface finish of those portions of the concrete structure which ar visible and with which people are most likely to come into contact. The conventional patching cements that are currently employed are comprised of Portland cement, number 60 grade silica sand, a little water and some glue. The resultant patching cement mixture forms a gritty, paste-like substance prior to curing.
In order for conventional patching cement to adhere to concrete structures to which it is applied, the concrete structures to be finished must first be wetted down with water. The patching compound is then applied with trowels or other tools. When wet, the patching compound is not particularly adherent to the concrete structure, so that a considerable amount of time is required to smooth a conventional patching cement onto a concrete structure s that it will adhere to the structure when dried.
Furthermore, once conventional patching compounds are applied, they dry with a rough, gritty finish. If the surface is to be painted, a concrete structure finished with patching cement must still be sanded so as to increase the surface area which will be covered by a given quantity of paint. This is done to reduce the time required to paint the surface, and to reduce the amount of paint which will be required. Even so, a surface finished in this manner retains a certain grittiness which detracts from its appearance and which makes painting difficult and expensive.
If a surface finished with conventional patching compound is not painted, it takes on a dusty character. That is, conventional patching cements dry in such a manner that a powdery dust is given off when the surface is rubbed or contacted by passing articles, such as articles of clothing. Furthermore, the dusty nature of the dried patching cement is such that many persons experience a dry, unpleasant sensation in their nasal passages while breathing in the vicinity of concrete structures that are finished with conventional patching cement.
Another disadvantage of the use of conventional patching cement is the extensive waste and cleanup which is required. As previously noted conventional patching cements are not particularly adherent to concrete surfaces when they are first applied. As a result, a good portion of the patching cement fails to adhere to an elevated concrete structure, such as a wall or ceiling, and instead falls to the floor. An inordinate quantity of conventional patching cement is therefore required to finish such an upright concrete surface. Moreover, the wasted quantities of patching cement must be cleaned up, thus necessitating a further labor expense.